We have been continuing our investigations of the low spin iron center in nitrile hydratase, in collaboration with Mark Nelson and John Cummings of DuPont, who have provided us with frozen protein samples. EXAFS has identified two or three sulfur ligands to the iron center, with the remaining ligands being oxygen or nitrogen scatterers. Some minor changes are seen with binding of inhibitors (to the enzyme[unreadable]not necessarily to the iron center) such as phenylhydrazine or isobutyronitrile. We are currently in the process of modelling the EXAFS to give bond length distributions to see if this may give insight into the changes which are occuring on the binding of these inhibitors. SCIENTICIC SUBPROJECT 61